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Thursday, March 20, 2008

Well, I'm up early, and it's still dark outside, because we have been under the domain of Daily Time for a couple weeks, now. The sunrise above, is what it might look like here in an hour or more.

Getting up early sometimes leads me to wondering perennially stupid questions, at least if I'm not woken up by work worries or other things, which is fortunately not usually the case, unless I'm overly concerned about drill rigs or things like that. Questions:

How large will the Basin and Range and Intermountain West become in the next 10 to 50 million years?

Is the entire Basin and Range underplated by core complexes that we simply haven't seen yet (because they are presently too deep to see)?

Will the ocean move into the rifted Intermountain West before Las Vegas or Los Angeles can steal northern Nevada's groundwater?

Will we discover a "Walker Lane of the East" somewhere, somehow bounding the eastern part of the Great Basin the way the Walker Lane more or less bounds the western part?

Will the mantle (or "Serpentosphere"??) ever be proven to be a source of methane? And will we tap it for energy by drilling deep into the San Andreas fault?

Will we survive the next 300 years of natural and user-enhanced global warming (according to Milankovitch cycles, much pooh-poohed by many geologists, we will reach a temperature peak naturally in about 300 years, and in fact are already over the main temperature hump toward a long cooling trend)?

And what will our slide into the next ice age bring in the years following that upcoming peak be like (provided, of course that we don't change all that)?

Will Yellowstone erupt sometime within the next 500,000 to 1,000,000 years (or Any Day Now), thereby putting an immediate halt to any current man-made and natural global warming?

Will geologists discover a gold deposit in the present locality of the Mendocino Triple Junction in 1 to 3 million years, which would be similar to the McLaughlin gold deposit near Clear Lake, CA , which formed within a couple million years of the triple junction passing through that area?

These are the things that wake geologists up in the middle of the night! Stay tuned to find out the answers, if any are forthcoming.

7 comments:

Which geologists poo-poo Milankovitch cycles? I sometimes grind my teeth when people try and match every wiggle in their cores to orbital forcing without independent age control, but the orbital control over glacial-interglacial variations for the last few million years is generally accepted as pretty solid, I think.

"Will the ocean move into the rifted Intermountain West before Las Vegas or Los Angeles can steal northern Nevada's groundwater?"

It seems we are at a relatively stable highstand (stillstand?) in sea level at present...it's about 130 m higher than at Last Glacial Max (LGM). It rose quickly from 18 ka to about 6 ka and has been slowly rising to nearly stable since then. I haven't done the research, but it seems it would still take quite a bit more to flood the interior basins. Even the projected rises, which have a significant impact on our civilization, aren't that big in the grand scheme of things.

And, I would echo Chris in wondering which geologists don't agree with orbital geometry-influenced climate cycles and why.

Warren Hamilton explained quite clearly today, at the GSA Cordilleran/Rockies section meeting, that the Great Basin is stretching northwestward because it's chasing the Pacific plate. That change of direction, from westward to NWward, is what has formed the Walker Lane. No such dynamics obtain along the Wasatch Front.

I am very impressed by your early morning pre-coffee clarity and eloquence! My usual first geological question of the day is, "Did I sleep through any earthquakes last night?"I have, however, taken a good hour to fall asleep (after I turned off the light) due to pondering the existence/behavior of the Garlock Fault.

Have gold deposits been found at other sites of former triple junctions?

The book my intro geology class used was all in favor of Milankovitch cycles. They are not teaching the newbies to poopooh it!

Even if getting usable energy from mantle heat via tapping into faults never actually happens, it would be a really awesome thing to work into a science fiction story.

CJR, Brian, and Julian, I'm glad to hear about Milankovitch cycles - it's just seemed that so much these days relies on computer models - and that's so esoteric to me. (And Chris, I hadn't seen your archive before!)

Brian, you're right, it would take a lot to flood the highly elevated Nevada (like tens of millions of years and a different plate tectonic scenario, really) - but I hope the southerners (L.V. and L.A.) don't get all the water!

Andrew, I'm sorry I'm missing the Cordilleran section meeting. Sounds like a great talk by Warren Hamilton. I've always kind of thought of the Wasatch and the Rocky Mountains as holding the east side of the Great Basin in place so it can stretch apart in its WNW-ESE direction - as though the Wasatch was acting as the east side of a Walker-Lane-parallel right-lateral Riedel shear, even though no actual movement in that direction is taking place -- but that's probably a pretty simplified and inaccurate way of looking at things. Enjoy the meeting!

Julian, I don't know about what has happened at other triple junctions, but that's a good question! Along the San Andreas south of Mendocino and south of Clear Lake, there are several volcanic fields and mercury districts, which are older southward until you reach the New Idria district, and south of that there are oil fields. I think there was a USGS Professional Paper tentatively correlating all those things with the time that the triple junction passed through.

Silver Fox says: "...it's just seemed that so much these days relies on computer models"

I hear ya. Modeling definitely has its role in earth science, but some modelers hyperbolize its role as the end-all-be-all, the thing that will answer everything. Not all modelers do that, of course, but I've heard that sentiment before.

On the flip side, I've also heard the sentiment from field geologists that all questions can be answered by solely "old school" techniques.

I'm constantly doing my best to be an "integrator". We need to do it all ... field work, modeling, re-evaluation of existing work, quantitative analysis, qualitative analysis, and so on, and so on.

Brian, integrators (and mult-disciplinarians) are always needed. For a time, at least, a lot of people were deep in their own specialties - and maybe that's not the case so much any more. (I don't mean in climatology specifically, by any means.)